He and his wife Michelle have told their two daughters that if they opt for a tattoo they will do the same, and then post the results online.

"What we've said to the girls is, 'If you guys ever decided you're going to get a tattoo, then mummy and me will get the exact same tattoo in the same place. And we'll go on YouTube and show it off as a family tattoo,'" Mr Obama told NBC, in an interview filmed before the Boston Marathon bombings.

"And our thinking is that might dissuade them from thinking that somehow that's a good way to rebel."

With every other celebrity seemingly sporting a tattoo, as well as 36 percent of 18 to 25 year-olds in the United States, the president appears to have grown concerned that his daughters, Malia 14, and Sasha, 11, may follow the growing trend. By contrast, just 11 per cent of the Obamas' 50-64 age group admit to having a tattoo.

"I do have to warn the parents who are here, who still have young kids, they grow up to be, like five feet 10 inches. And even if they're still nice to you, they basically don't have a lot of time for you during the weekends.

"They have sleepovers and dates. So all that early investment just leaves them to go away," he said at a public event.

The first lady has said that parental anxiety, rather than the burdens of office, was turning the 51-year-old president’s hair grey.

Mrs Obama told ABC: “Fathers in particular, I don’t think they really know how they’re going to feel until it happens. There’s nothing like the look on his face when Malia dresses up for a party, and is heading out. She walks past him and you can see his face just drop a little bit,” she said. “He’s like ‘who was that?!’”

Mr Obama admitted that he had not set a great example to his girls when he praised California's Kamala Harris as "the nation's best-looking attorney general".

He described the incident as "a useful teaching moment for me and for the country".

"As the father of two daughters, I want to make sure that they're judged on the merits and not on their appearance," he said.

"I've got no problem in people, I think, using what was intended as an innocuous comment to make this larger point that we want to make sure that women are judged based on the job they do and not how they look."